When towing a trailer behind a vehicle, one factor that can significantly affect safety is the tongue weight or static downward force that the trailer applies to the hitch of the tow vehicle. If the tongue of the trailer does not apply enough downward force to the hitch, a dangerous condition called trailer sway could result. If the tongue of the trailer applies too much downward force to the hitch, then the rear tires of the tow vehicle can be overloaded, thus pushing the rear of the vehicle around and compromising steering and/or braking of the tow vehicle. A generally acceptable tongue weight for any trailer is somewhere between 9% and 15% of the gross trailer weight (GTW). Measuring tongue weight typically involves weighing the tongue weight of the trailer when decoupled from the tow vehicle, which can be time consuming and dangerous. In addition, for safe and comfortable towing, the trailer should be as level as possible. A level trailer will put less strain on the connection between the trailer and the hitch and will also help the trailer stay in line behind the tow vehicle.